Circuit breaker contact separation initiator



. P 9, 1969 J. c. BRUMFIELD 3,466,578

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR Filed June 26, 1967 3Sheets-Sheet 1 v 1 IN VEN TOR. JON/V C BRO/141 7620 M MM Se t. 9, 1969J. c. BRUMFIELD 3,465,573

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR 3 Sheets-Sheet 2 Filed June26, 1967 m. Rm 3 M f h C x m J W m n uk m Sept; 9, 1969 J. c. BRUMFIELD3,466,578

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR United States Patent M3,466,578 CIRCUIT BREAKER CONTACT SEPARATION INITIATOR John C.Brumfield, Philadelphia, Pa., assignor, by mesne assignments, to I-T-EImperial Corporation, Philadelphia, Pa., a corporation of Delaware FiledJune 26, 1967, Ser. No. 648,557 Int. Cl. H01h 71/16, 9/20 US. Cl.335-172 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to anelectric circuit breaker contact separation initiator and moreparticularly to a structure secured to the tripper of the circuitbreaker which engages the movable contact or its support arm to initiateseparation of the movable contact from the stationary contact.

In recent years considerable effort has been expended in the electricalindustry to reduce the size of circuit protective equipment. Forexample, in the area of small air circuit breakers of the type withwhich the instant invention is intended to cooperate, the industry hasseen acceptance of one-half inch wide circuit breakers as a substitutefor the long accepted one inch wide breaker. Further evidence of thepresent emphasis on reduction in size and simplicity in design isevidenced by United States patent application Ser. No. 587,709 filedOct. 19, 1966, now Patent No. 3,377,574, entitled Circuit BreakerResetting and Closing Mechanism, and assigned to the assignee of theinstant invention, where there has been described in great detail anovel circuit breaker which has achieved utmost simplicity in design andmaximum reduction in overall size.

Simultaneously with the development of smaller and more simplifiedcircuit breakers, and related thereto, engineers have re-examined theoperating characteristics of small circuit breakers and looked for waysin which their operation might be simplified.

Circuit breakers with which the present invention are employed have astationary contact and a movable contact, which is normally inengagement with the stationary contact and which is supported by an arm.The circuit breaker has a tripper, comprising a cradle, which ispivotably mounted at one end thereof, and at the other end thereof it issupported by a latch. The cradle is normally biased to pivot in a mannerto trip apart the circuit breaker contacts. The latch supports thecradle against the force exerted upon the cradle by biasing means.

Circuit breakers of the prior art make use of a toggle consisting of thecircuit breaker operating handle, the movable contact of the breaker orthe contact support arm, and a pivot point between these two elements.An over-center spring is provided for causing the toggle to collapseeither in a direction which secures the movable contact against astationary contact or in the opposite direction which snaps the movablecontact away from the stationary one. No separate contact separationinitia- 3,466,578 Patented Sept. 9, 1969 tor is provided other than thetoggle and overcenter spring themselves.

In small circuit breakers, it is necessary to have all movement of thecomponents take place within a rather confined space. To minimize themovement necessary to initiate separation of the contacts, the presentinvention provides a contact separation initiator which initiatescontact separation before the normal action of the toggle andover-center spring would initiate separation.

The cradle portion of the tripper has thereto connected the contactseparation initiator of the present invention. The initiator is sopositioned on the cradle, that once the latch releases the cradle andthe cradle begins to pivot, the initiator engages the movable contactsupport arm and moves the movable contact away from the stationarycontact thereby initiating contact separation.

In the prior art, initiators are known which are pivotally connected tothe cradle. However, such initiators are complicated structures, requiremolding of circuit breaker casings to close tolerances and take up extraspace in crowded casings. See US. Patent No. 2,996,589, entitled PivotedBirnetal, issued to Felix Myers, and assigned to the assignee of thepresent invention.

In the embodiment shown in detail herein, the initiator is comprised ofa projection fixedly attached to the cradle. The initiator is positionedto strike the movable contact support arm after the cradle has begun topivot once it is released by the latch. The initiator need not befixedly connected to the cradle so long as it is so connected with thecradle that it is brought into engagement with the support arm of themovable contact once the cradle has begun to pivot upon its beingreleased by the latch.

The present invention is being illustrated in detail in conjunction witha circuit breaker shown in aforementioned application Ser. No. 587,709,new Patent No. 3,377,574, in which embodiment the movable contactsupport arm pivots on a pivot point on the cradle and the over-centerspring is connected between the movable contact support arm and theoperating handle of the circuit breaker. The present invention may beemployed in conjunction with any other type of circuit breaker employinga tripper, supported by a latch type device, which tripper pivots whenthe latch type device releases its support of the tripper. For instance,the present invention might be mounted on the cradle of a circuitbreaker shown in US. Patent No. 2,996,589 issued on Aug. 15, 1961, toFelix Myers, entitled Pivoted Bimetal and assigned to the assignee ofthe instant invention. This latter patent illustrates a circuit breakerwherein the movable contact support arm pivots not on the cradle but onthe operating handle and the overcenter spring is connected between themovable contact support arm and the cradle, rather than between themovable contact support arm and the operating han le.

It is an object of the present invention to provide a circuit breakercontact separation initiator which initiates the separation of thecontacts after minimum movement of the circuit breaker tripper.

It is another object of the invention to provide a circuit breakercontact separation initiator adaptable for use in a circuit breakerhaving limited interior space.

It is another object of the present invention to provide a circuitbreaker contact separation initiator for use in conjunction with .acircuit breaker employing a pivotable tripper.

Other objects and a fuller understanding of the instant invention may behad by referring to the following description and drawings, in which:

FIGURE 1 is an exploded perspective View of the internal components of acircuit breaker constructed in accordance with the teachings of theinstant invention,

and including the circuit breaker contact separation initiator of theinstant invention;

FIGURE 2 is a plan view, with the cover removed, of the circuit breakerof FIGURE 1, with the circuit breaker mechanism thereof in the closed oron position;

FIGURE 3 is a plan view of the circuit breaker of FIGURE 2 showing thecomponents thereof shortly after the tripping mechanism has tripped thecircuit breaker; and

FIGURE 4 is a plan view of the circuit breaker of FIGURE 2 in the fullytripped position.

Referring to FIGURE 1, there is shown the internal mechanism of acircuit breaker constructed in accordance with the principles of theinstant invention. It is reemphasized that although the circuit breakercontact opening initiator 43 of the instant invention will bespecifically described with respect to the internal mechanism 10 shownin aforementioned application Ser. No. 587,709, now patent No.3,377,574, such disclosure is intended in no way to limit theapplication of the instant invention.

Similarly, it is to be understood that although the instant inventionwill be described with respect to a circuit breaker for the protectionof a single phase of current, the instant invention can be readilyemployed in a multiphase circuit breaker -by positioning an initiator onthe tripper in every phase of a multi-phase circut breaker.

* The circuit breaker mechanism 10 includes the common mounting plate11, which is integrally provided with the following parts: an upstandingcradle-pivoting tab 12; an upstanding relatch mechanism pivoting tab 13;an upstanding tripper mechanism pivoting tab 14 and an upstanding springretaining tab 15. In addition the plate 11 includes an elongated slot16; a generally centrally located operating handle pivoting aperture 17;and an arcuate slot 18 which receives an upstanding tab portion 23 ofthe operating handle 20, as hereinafter described.

The operating handle '20 of the circuit breaker includes an upstandingknob receiving tab 21 at one end thereof, and a pair of upstanding tabs22 and 23 at the opposite end thereof. Tab 22 is provided with anopen-ended slot 24 which fits over a pivot portion 25 of the mountingplate aperture 17 whereby the operating handle 20 may experiencerotation in a plane parallel to the plane of the mounting plate 11 aboutthe point 25. The second tab 23 of the operating handle 20 is freelyreceived within the arcuate slot 18 and extends forward of the mountingplate 11 when the operating handle 20 is placed behind the mountingplate 11, with the open-ended slot 24 riding on the point 25.

Biasing means in the form of spring 27 is secured at one end thereof tothe tab 23 and at the opposite end thereof to the upstandingspring-retaining tab so as to constantly bias the operating handle in acounterclockwise direction in FIGURE 1 about the pivot defined by thepoint 25.

A cradle 30 is provided and includes a bifurcated end 31, the two arms32 of which include aligned apertures 33 which receive the cradlepivoting tab 12 of the mounting plate 11. The opposite end of the cradle30 includes an upstanding latch tip 34 which cooperates with the latch59 of the tripping mechanism 55, as will be described in further detail.Intermediate the ends of the cradle 30 is an overturned tab 35 whichcooperates with an open-ended slot 41 provided at one end of a movablecontact support arm to permit rotation of the movable contact arm 40about point 37 on the cradle 30 when the movable contact arm 40 isinserted up and under the over-turned tab 35.

Cradle 30 has attached to it the circuit breaker contact separationinitiator 43, shown clearly in FIGURE 1. The initiator 43 shown inFIGURE 1 is comprised of a projection extending outward from the side ofthe cradle 30. The cradle 30, as has been noted above, is pivotallymounted at its end 31 on pivot projection 12, whereby the cradle 30 isenabled to pivot in a manner more fully described below.

While the initiator 43 is shown as being fixedly mounted on the cradle30, it may be otherwise connected with the cradle 30, so long as it isadapted to move into engagement with the support arm 40 of the movablecontact, once the cradle 30 begins to pivot, as described below.

Since the present invention may be employed in a circuit breaker wherethe movable contact support arm and the tripper for the contact are notin close proximity, the initiator 43 merely must comprise a structure soconnected with the tripper as to be able to engage the movable contactsupport arm when the tripper has begun to operate. The operation of theinitiator 43 will be described below in conjunction with the descriptionof the trip operation of the circuit breaker.

In the specific embodiment illustrated in the figures, the

movable contact arm 40 is mounted directly to the cradle 30 and isadjacent to the side of the cradle upon which projection 43 ispositioned.

The end of the movable contact arm 40 opposite notch 41 integrallycarries a generally S-shaped spring-retaining portion 45 and alsocarries a generally L-shaped portion 46 which carries the movablecontact pad 47 thereon. Disposed opposite the movable contact pad 47 isa stationary contact pad 48 secured to the terminal 49 of the breaker.The contact pads 47 and 48 comprise the cooperating contacts in thebreaker.

A main operating spring 50 is secured at one end thereof to thespring-retaining portion 45 and at the opposite end thereof to aspring-retaining portion 51 which is an integral portion of theupstanding knob-retaining portion 21 of the operating handle 20.

The tripping mechanism generally designated at 55 includes a bimetallicelement 56 for responding to moderate or time delay overloads; andincludes a magnetizeablev element 57 and a fixedly mounted armature 58adjacent to element 57 for attracting element 57 when it is magnetizedby a high fault current.

Tripping mechanism 55 has an aperture 58a ihrough which is passedmounting plate tab 14 about which tab tripping mechanism 55 is enabledto pivot.

Latch 59 is connected with both of elements 56 and 57 and is removedfrom its supportive position with respect to latch tip 34 of cradle 30whenever either of elements 56 and 57 is activated. The trippingmechanism is explained in greater detail in copending patent applicationSer. No. 692,561 filed Dec. 21, 1967, in the name of F. Meyers and W.Goodnow, entitled Circuit Breaker Thermal and Magnetic TrippingMechanism, which is assigned to the assignee of the instant invention.

An automatic relatching means may be employed in conjunction with thecircuit breaker mechanism 10. The automatic relatching means 60 is morefully described in aforementioned copending patent application Ser. No.587,709, now Patent No. 3,377,574, and includes first and second members61 and 62 respectively, which are joined as by a pin 63 for rotationrelative to one another. The first member 61 includes a centrallylocated aperture 64 which is received and carried by the upstandingpivot tab 13 on mounting plate 11 to permit rotation of the linkageassembly relative to the plate 11. The second member 62 terminates in anupstanding actuating surface 65 which itself terminates in a rearwardlydisposed portion 66 which lies in a plane behind the planar surface ofthe second member 62 so that it may ride behind the mounting plate 11with the upstanding actuating surface 65 projecting through theelongated slot 16 and beyond the front surface of the plate 11.

Current flow through the circuit breaker is through the path defined byterminal 49, stationary contact pad 48, movable contact pad 47,conductive braid 70, bimetallic element 56, conductive braid 71 andterminal 72. When the circuit breaker is tripped, the current path isbroken at the point of contact between terminals 47 and 48.

The circuit breaker components shown in exploded perspective in FIGURE 1are shown assembled in a circuit breaker casing 80 in FIGURE 2. Thecasing normally includes a cover, not shown, which when removed revealsthe mechanism within the casing.

The operation of the circuit breaker, and especially the role of thecircuit breaker contact separation initiator in the present invention,will now be described. In FIG- URE 2, the circuit breaker is in the onor closed position, i.e., the contact pads 47 and 48 complete thecurrent path through the breaker. The latch 59 of tripping mechanism 55is in abutting, blocking engagement with respect to latch tip 34 ofcradle 30.

Operating spring 50 draws spring retaining portion 45 of movable contactarm 40 toward spring retaining tab 51 on operating handle 20. A togglecomprising spring retaining portions 45 and 51 and pivot point 37 isformed. The spring 50, pulling on spring retaining portion 45, attemptsto cause the aforementioned toggle to collapse to the right, as viewedin FIGURE 2, pulls the movable contact support arm counterclockwise, andpresses movable contact pad 47 into secure engagement with stationarycontact pad 48. Because the toggle is unable to collapse to the right,the movable contact support arm 40 pushes on pivot point 37 in suchmanner that cradle 30 would be pivoted clockwise about its pivot 12,were it not for the fact that latch 59, in engagement with latch tip 34of cradle 30, supports cradle 30 stationary and prevents its pivotingaround pivot 12.

Starting with the circuit breaker in its closed condition of FIGURE 2,and turning now to FIGURE 3, it will be assumed that a time delay orinstantaneous fault current has been detected by tripping mechanism 55,which rotates latch 59 clockwise, as viewed in FIGURE ,3, from itsblocking position with respect to latch tip 34 of cradle 30.

FIGURE 3 illustrates the situation immediately after latch 59 hasreleased latch tip 34. Movable contact support arm 40 is stillsubstantially in the position shown in FIGURE 2. The pull exerted byspring 50 on spring retaining portion 45 pulls portion 45 toward springretainer 51. This exerts a pull on pivot point 37 of cradle 30, thuscausing the cradle, which is no longer restrained by the latch, to beginto rotate clockwise. The toggle formed of spring retainers 45 and 51 andof pivot point 37 begins to collapse to the right, as viewed in FIGURE3, whereby the movable contact 47 wipes over the surface of stationarycontact pad 48, while the force of spring 50- retains these contacts insecure engagement.

In FIGURE 2, with the breaker in the closed condition, note that contactseparation initiator or projection 43 is spaced slightly away frommovable contact support arm 40. Turning to FIGURE 3, as cradle 30 beginsto rotate clockwise, pivot point 37, moves upward, and because thetoggle comprised of retaining portions 45 and 51 and pivot point 37 iscollapsing, movable contact support arm 40 experiences slight rotationcounterclockwise, as viewed in FIGURE 3, about pivot 37. At the sametime, cradle 30 is pivoting clockwise about its pivot 12 and thepivoting of cradle 30 and of contact arm 40 soon brings projection 43into abutting engagement with contact support arm 40. By the timeprojection 43 first engages contact arm 40, cradle 30 and support arm 40are both pivoting rapidly, respectively, clockwise and counterclockwise.Projection 43 strikes support arm 40 with an impact suflicient toseparate movable contact pad 47 from stationary contact pad 48 andsufficient also to drive movable contact support arm 40 over-center pastpivot point 37.

The initial impact provided by projection 43 against contact support arm40 is suflicient to drive support arm 40 over-center. Therefore, supportarm 40 and projection 43 are only instantaneously in engagement. Spring50 must be sufliciently weak that it will not prevent movable contactsupport arm 40 from pivoting over-center past pivot 37.

As cradle 30 is rotating, when point 37 passes to the right, as viewedin FIGURE 4, of the force line of spring 50, the toggle formed by springretainer 51, point 37 and portion 45 collapses to the left. Once spring50 has passed beyond, or to the left as viewed in FIGURE 4, of the tab22 of operating handle 20, the handle 20 rotates counterclockwise fromits position of FIGURE 3. At this stage, spring 50, although notnecessarily completely relaxed, is not sufficiently tensed to rotatehandle 20 counterclockwise all the way to its position of FIG- URE 4.

Spring 27, attached to tab 23 of handle 20, is provided to pulloperating handle 20 further counterclockwise, thereby moving handle 20all the way to the tripped position of FIGURE 4.

As can be seen in FIGURE 4, cradle 30 rotates clockwise until it abutsrelatch actuating surface 65. Movable contact support arm 40 rotatesclockwise until its portion 45 abuts upturned tab 81, wihch preventsfurther opening of contact 47.

The apparatus for relatching the circuit breaker is not part of thepresent invention and is fully described in aforementioned copendingapplication Ser. No. 587,709, now Patent No. 3,377,574. Briefly, torelatch the circuit breaker for another trip operation, handle 21 isrotated from its position of FIGURE 4 clockwise to its position ofFIGURE 2. A projection 82 on handle 20 strikes actuating surface 83 ofrelatch mechanism 61 and causes the mechanism to pivot clockwise aboutits pivot tab 13. The pivoting element 61 draws link 62 to the left, asviewed in FIGURES 2 and 4, and pulls actuating surface 65 against cradle30. As surface 65 moves to the left, as viewed in FIGURE 2, cradle 30 ispivoted counterclockwise about its pivot 12 to the position of FIGURE 2,where the latch tip 34 again engages the latch 59.

When the operating handle 21 passes over pivot point 37, operatingspring 50 snaps movable contact arm 40 counterclockwise, as viewed inFIGURE 2, and movable contact 47 is snapped into engagement withstationary contact 48, thereby placing the circuit breaker of FIG- URE 2in the closed or on position.

There has just been described a circuit breaker having a contactseparation initiator which is connected with the tripper of the circuitbreaker, in order to initiate the separation of the movable contact ofthe breaker from the stationary contact upon, the occurrence of a faultcurrent.

Although this invention has been described with respect to its preferredembodiments, it should be understood that many variations andmodifications will now be obvious to those skilled in the art, and it ispreferred, therefore, that the scope of the invention be limited not bythe specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. In a circuit breaker comprising,

a cooperating contact assembly comprising a movable contact assembly anda stationary contact;

a tripper connected with said movable contact assembly; said tripperbeing movable to a first position, wherein said movable contact assemblyand said stationary contact are in engagement, and to a second position,wherein said movable contact assembly and said stationary contact havebeen tripped apart;

a means for supporting said tripper in the first position and a meansfor urging said tripper to the second position;

the improvement comprising, said tripper having thereto connected acircuit breaker contact separation initiating means; said movablecontact assembly being operatively positioned, with respect to saidtripper, and said initiating means being operatively positioned, withrespect to said tripper, so that as said tripper moves from its first toits second position upon removal of the said supporting means for saidtripper, said movable contact assembly is caused to travel in adirection toward said initiating means and said initiating means iscaused to move toward said movable contact assembly so as to cause Saidinitiating means to engage said movable contact assembly and to initiatethe separation of said movable contact assembly from said stationarycontact;

said initiating means comprising a member fixedly mounted to saidtripper.

2. In the circuit breaker of claim 1,

said tripper comprising a cradle; a first pivot for said cradle; saidcradle being pivotably mounted on said first pivot for pivoting betweenits said first and second positions;

the improvement comprising, said initiator being fixedly mounted to saidcradle.

3. In the circuit breaker of claim 1,

said movable contact assembly comprising a movable contact and a supportarm for said movable contact;

the improvement comprising, said initiator being engageable with saidsupport arm.

4. In the circuit breaker of claim 3,

' the improvement further comprising, said initiator contact and asupport arm for said movable contact; with improvement comprising, saidinitiator being engageable with said support arm.

References Cited UNITED STATES PATENTS 1,610,213 12/1926 De Ville.2,902,560 9/1959 Stanback. 3,171,921 3/1965 Woods. 2,934,624 4/ 1960Middendorf.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner U.S.Cl. X.R.

